This invention relates generally to ventilation of the interior of an automobile cabin. More specifically, this invention relates to a system with voice-controls for ventilating an overheated automobile cabin by using convection to convey hot air out of the cabin, and by using evaporation to cool the driver's perspiring face and body.
When vehicles are parked in the sun, heat can build up quickly in the cabin. The seats, dash and other interior features begin to absorb the sun's energy and radiate it into the cabin. With the windows and doors closed, air does not circulate to remove the heat. In the desert southwest and other hot climates, the interior temperature of a closed vehicle can reach a scorching 140 degrees or more in a matter of minutes.
When a driver returns to his vehicle after it has been sitting in the sun, getting into the vehicle can be quite uncomfortable, as the pent-up, searing heat envelopes the driver. Because of the large volume of space inside a vehicle, cooling the interior takes many minutes as the volume of hot air must be displaced with cooler air. To speed the cooling of the interior, the driver typically turns on the air conditioner as soon as the vehicle is started. The air conditioner then works at full capacity to chill the overheated cabin air, causing a severe load on the air conditioning unit and the vehicle engine.
To ventilate the cabin of a vehicle after it has been sitting in the sun, the prior art describes several systems to blow the hot air out of the cabin. In U.S. Pat. No. 5,238,447, Weissbrich et al. (Weissbrich '447) describe a system to allow hot air to rise and escape through a car's sunroof. When the interior temperature of the car is hotter than a predetermined threshold, if the door is unlocked or the ignition key is inserted in the ignition, the sun roof opens automatically. Simultaneously, a ventilator may be turned on to help push hot cabin air out of the roof opening. The system is powered the vehicle's battery or a solar battery.
In U.S. Pat. No. 5,259,814, Weissbrich et al. (Weissbrich '814) describe a system in which the temperatures inside and outside the cabin are measured and compared to thresholds. If the inside temperature is greater than the outside temperature and greater than the threshold temperature, the windows automatically open to allow hot air to drift out. If the inside temperature is greater than the outside temperature but less than the threshold temperature, the windows automatically close to keep warmer air in. When the interior temperature is less than the outside temperature and less than a threshold temperature, the windows close and a fan conveys relatively warmer air from the outside into the cabin. The fan is preferably placed near the vehicle window. The system may run when the motor is off or on.
U.S. Pat. No. 5,222,661 issued to Wenhart describes a system for automatically cooling the interior of a vehicle by opening a window and using the fan of the vehicle's own ventilation system to blow hot cabin air out of the cabin's windows when the interior temperature exceeds a given threshold.
As these examples show, the prior art is based on the idea of blowing all the hot air out of the cabin, typically through the window or roof vents that have been automatically opened. U.S. Pat. No. 4,497,240 issued to Nagatomo describes a variation on these systems in which vehicle's existing air flow system is employed while the car is parked and unoccupied. The system uses the fan native to the car to circulate cabin air within the vehicle or to introduce external air through the duct that connects the cabin to the outside, via a damper. The windows are not opened to vent the cabin. A power source separate from the vehicle's power source supplies power to the built-in cooling system when the car is not on. The temperature inside the cabin is measured and when it exceeds a predetermined temperature, the vehicle's fan is turned on to blow outside air into the overheated cabin or, conversely, to exhaust hot cabin air.
While the prior art may be effective in removing hot air from the cabin, it does not take advantage of another method of cooling: evaporation. If the cabin of the car becomes too overheated for the driver to be comfortably seated, typically the driver will perspire as the cabin is opened. If air is then drawn across the driver's sweaty skin, evaporation will remove the heat from the skin and the driver will feel cooler. In the prior art, instead of drawing the relatively cooler outside air across the driver's face and body, the relatively hotter air from inside the cabin envelopes the driver as the air makes its way to the window or roof near the driver's head. This air flow has the undesirable effect of extending the time the hot cabin air is in contact with the driver.
Therefore, it is an object of this invention to improve the prior art of automobile cabin ventilation by providing a system which takes advantage of evaporation of driver's perspiration. Another object of this invention is to provide a vehicle ventilation system in which the cooling effect is felt immediately by the driver. Another object of this invention is to provide a ventilation system which begins operation at the driver's command, particularly when the driver returns to his vehicle that has been sitting in the scorching heat. A further object of this invention is to provide voice-activated controls for various system parameters. Another object of this invention is to provide a simple., low-cost ventilation system which can easily be installed in a vehicle during production or as an after-market purchase.